---
title: "Building on Koh Samui: the realities — Stellar Property Global"
description: "Building on Koh Samui: slopes, drainage, the rainy season, permits and materials by ferry, from our builds in Lipa Noi, Lamai and Thong Krut."
language: "en-US"
content_type: "article"
canonical_url: "https://www.stellarpropertyglobal.com/articles/island-construction-realities-koh-samui"
image: "https://www.stellarpropertyglobal.com/api/media/file/spg-villa-aerial-1200x630.jpg?prefix=recovery%2F09e95153-1e5d-475a-8811-239da1d74bcf"
image_alt: "Aerial view of a tropical villa surrounded by palms."
date_published: "2026-05-29T03:00:00.000Z"
date_modified: "2026-10-11T11:11:05.097Z"
author: "Stellar Property Global"
topic: "Building in Koh Samui"
tags: ["Lipa Noi","Lamai","Thong Krut","Portofino Village","South Beach Inn"]
---

# Building on an island: slopes, soil, rain and permits on Koh Samui

What actually shapes a build on Koh Samui: sloped plots, water off the hills, the rainy season, permits and materials that cross by ferry. Told from our own sites.

[Building in Koh Samui](/articles/topic/building-in-koh-samui)

[Stellar Property Global](/articles/author/stellar-property-global)

Company editorial team

Published on May 29, 2026

![Crew pouring footings in excavated trenches on a building site in Lamai, Koh Samui](/api/media/file/mcp-5320ecdb70d38c9034759ca466a531b7-m170-island-construction-realities-koh-samui-hero.webp?prefix=recovery%2Fdfbf34fc-6ac1-460b-8a51-90b15ed88406&2026-10-10T06%3A55%3A19.842Z)

Building on Koh Samui is shaped by five things a mainland build rarely meets all at once. Many plots are sloped, so the ground has to be held before anything stands on it. Heavy rain runs off the hills and has to be led away.

The rainy season, roughly October to December, decides when you can dig and pour. Permits depend on the plot. And almost every bag of cement and length of steel crosses from the mainland by ferry.

We have built on hillsides in Lipa Noi, on a hill-fed site in Lamai and on the beach at Thong Krut. This guide explains how each of those realities works on site.

This article is about the mechanics. For the money and the timeline, read our build pillar, [what it costs and takes to build a villa on Koh Samui](/articles/cost-to-build-villa-koh-samui).

## Slopes: why the ground comes first

The sea views most people want on Koh Samui usually come with a slope. A slope changes the order of work. Before a house goes up, the ground must be cut, filled and held in place.

![Villa Emerald from the hillside at Portofino Village, Lipa Noi](/api/media/file/mcp-1d32781a6e9af5d1af4f9ca515a27086-m050-portofino-village-gallery-1.webp?prefix=recovery%2F1845747d-8f70-4739-9ef2-480808b65d7c&2026-10-10T06%3A16%3A21.900Z)

A retaining wall is a wall built to hold back soil on a slope, so the ground above it cannot slide onto, or out from under, what you build. On a steep plot it is often one of the first structures on site. It is also one of the last things anyone admires, because once the garden goes in you barely see it.

Our clearest hillside example is [Portofino Village, our villa development above Lipa Noi](/developments/portofino-village). The villas sit on levels up the hill: the Villa Pearl plots on the first level, Villa Emerald and another villa on the second.

Each level gives the one above it a view over the one below. That layout only works because the ground at every level is shaped first.

A slope also gives you space below the main floor. At Portofino Village, Villa Pearl Plot 3 has underground rooms, including a massage and gym area.

Another villa there has an underground cinema room and bar. Villa Emerald has stairs beneath its pool terrace.

## Water and soil: drainage you never see

On Koh Samui, rain falls on your plot and also runs down from the hill above it. A site has to be built to take that water and send it somewhere safe.

![Reinforced drainage channel under construction on a building site in Lamai, Koh Samui](/api/media/file/mcp-0a5f7689468478057820d7ba9760e0c3-m171-island-construction-realities-koh-samui-inbody-after.webp?prefix=recovery%2Fd0ba0a7b-ebdb-463c-bb8b-f2dd68b56675&2026-10-10T06%3A55%3A38.123Z)

The clearest example we have is an extension we built for a client's gym in Lamai: a new gym area, pool and café. The site sits below higher ground. Early in the build, in February 2025, we laid a drainage system sized to carry rainwater coming down from the mountain and push it where it should go.

Before that, in January 2025, the same site was filled with laterite and levelled with a backhoe. Laterite is a compact red clay-and-gravel fill, common on the island, used to build up and firm a site.

Only then did excavation for the main structure begin, in March 2025. Foundations followed in two stages in April.

The order matters more than the materials:

- Get access in first. On the Lamai site, the first work was excavating the road and car park.
- Fill and level the ground.
- Lay the drainage before the building, while the trenches are easy to dig.
- Then dig and pour the foundations.

If drainage is an afterthought, water finds its own route, often under a slab or behind a wall. Fixing that later means breaking open finished work.

## The rainy season sets the calendar

Koh Samui's heaviest rain falls roughly from October to December. Digging, pouring concrete and roofing are all harder in that window, and some days they stop.

*On Instagram: [See this on Instagram](https://www.instagram.com/reel/DRCm158AqUH/)

A realistic plan puts groundworks and the main pours in the drier months where it can, and keeps work for inside a roof for the wet ones. When the weather does cost days, the crew has to make them back.

In November 2025, our team in Lamai was working late into the evening while the rain poured, to keep the client's extension on track.

Island builds also run long for reasons nobody fully controls. We planned to open [South Beach Inn, our 8-room hotel on Thong Krut Beach](/developments/south-beach-inn), at the end of November 2024. It opened in March 2025.

We say that plainly because any builder on the island has a story like it. The useful question is whether they tell you.

## The beach is its own kind of site

A beachfront plot is flat, but it brings salt air and sun on every surface. South Beach Inn sits directly on Thong Krut Beach. Since opening we have kept working on it: the Rockstar Room, the hotel's sea-view suite, was refreshed in May 2025, and the entrance was renovated in April 2026.

Finishes have to be chosen for the coast. When we renovated [MARS Eatery & Art, our restaurant, café and art space in Lamai](/developments/mars-eatery-art), we ran exterior colour trials on the wall itself. We picked the final tone for light, texture and coastal durability.

## Permits: start them with the design

Every build needs approval before work starts, and what you can build depends on the plot. Height, distance from the coast and the slope can all limit the design.

We do not treat permits as paperwork for later. Our practice is to start the approvals alongside the design, so the drawings are shaped by what the plot allows. The detail changes from plot to plot, so confirm it for yours with a licensed local architect, and with a Thai lawyer on anything about ownership.

If a builder is vague about which approvals your plot needs, treat that as a warning. Our checklist in [how to choose a builder on Koh Samui](/articles/how-to-choose-a-builder-koh-samui) covers the questions to ask.

## Materials cross the water

Koh Samui is an island. Steel, cement, tiles, glass and fittings reach it from the mainland by ferry. That puts a sea crossing into every order.

![Formwork on a hillside plot at Villa Pearl, Plot 4, Portofino Village, Lipa Noi](/api/media/file/mcp-3e9d0ed1267e88173f80ce6f13559e6e-m162-cost-to-build-villa-koh-samui-inbody-after.webp?prefix=recovery%2Fff07317e-cb6c-4d5c-94fe-1e5ea632266b&2026-10-10T06%3A52%3A49.549Z)

In practice it means these habits on site:

- Order early and in sequence, so the next stage's materials are on the island before the crew needs them.
- Check deliveries on arrival. A wrong batch costs a second crossing.
- Plan pours around what has actually arrived. Build the formwork, the temporary wooden mould that wet concrete is poured into, only when the concrete and steel for that pour are on the island.

Commercial jobs carry the same logic at a larger scale. We cover hotels, gyms and restaurants in [commercial construction on Koh Samui](/articles/commercial-construction-koh-samui).

## Questions people ask

### What is the hardest part of building on Koh Samui?

Usually the ground. On a sloped plot, cutting, filling, holding the soil and draining the water come before the house itself. That work is out of sight once the build is finished, which is why it is the easiest place for a cheap quote to cut corners.

### When is the rainy season on Koh Samui, and can you build through it?

The heaviest rain falls roughly from October to December. You can keep building, but digging, pouring and roofing slow down or stop on wet days. A good plan does the groundworks in drier months and keeps indoor work for the rain.

### Do I need a retaining wall?

If your plot is on a slope, very likely. A retaining wall holds back soil so the ground cannot move onto, or out from under, your building.

Whether you need one, and how big, depends on the slope and the soil. An engineer should decide that on site.

### Why do builds on Koh Samui take longer than on the mainland?

Materials cross by ferry, the rainy season takes working days, and sloped plots need more groundwork first. Our own hotel, South Beach Inn, was planned to open at the end of November 2024 and opened in March 2025. Plan for time beyond the first estimate.

### Who handles building permits on Koh Samui?

That should be agreed in writing before work starts. We start approvals alongside the design. Rules differ by plot, so confirm the requirements for yours with a licensed local architect, and with a Thai lawyer on ownership questions.

## Tell us about your plot

If you have land on Koh Samui, or a plot in mind, we can walk it with you and tell you what the ground, the water and the calendar will ask of a build. See [how we build for clients](https://www.stellarpropertyglobal.com/build), or [ask about building](https://www.stellarpropertyglobal.com/contact?intent=build).

## Tags

[Lipa Noi](/articles/tag/lipa-noi), [Lamai](/articles/tag/lamai), [Thong Krut](/articles/tag/thong-krut), [Portofino Village](/articles/tag/portofino-village), [South Beach Inn](/articles/tag/south-beach-inn)

## Stellar Property Global

Company editorial team

Property development and management perspectives from Stellar Property Global.

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